Change time at the Royal Exchange

The following sentence in The life of William Nicholson by his Son caused me to Google ‘Change Time’ to see what this referred to:

‘And daily congregated in the shop after change time six or eight or more of the leading merchants to gossip over politics and the affairs of the day …’

Rather amusingly, an explanation came up from our very own Mr Nicholson in The British Encyclopedia, 6 vols of 1809, which I thought worthy of sharing due to the severity of the punishments threatened:

In 1703, the following notice appeared in the public papers: "An act of the Lord Mayor and Court of Alder men is affixed at the Exchange, and other places in this City, by which all persons are prohibited coming upon the Royal Exchange to do business before the hours of twelve o'clock, and after the hour of two, till evening change: Wherein it is further enacted, that for a quarter of an hour before twelve the Exchange bell shall ring, as a signal of change time ; and shall also begin to ring a quarter of an hour before two, at which time the change shall end : and all persons shall quit it, upon pain of being prosecuted to the utmost, according to law. That the gates shall then be shut up, and continue so till evening change time; which shall be from the hours of six to eight from Lady-day till Michaelmas, and from Michaelmas to Lady-day from the hours of four to six; before and after which hours the bell shall ring as above said. And it is further enacted, that no persons shall assemble in companies, as stock jobbers, &c. either in Exchange Alley, or places adjacent, to stop up and hinder the passage from and to the respective houses thereabouts, under pain of being immediately carried before the Lord Mayor, or other Justice of the Peace, and prosecuted."